Method and apparatus using laminated foils for placing conductive preforms

ABSTRACT

A method and apparatus are disclosed for placing solder balls  320  on electronic pads  910  or  1010  on a component  900  or substrate  1000,  such as for a ball grid array (BGA) applicator  100.  The solder balls  320  are held to openings  202  in a foil  130  against a second layer  350  by a holding force, whereby the second layer is of a porous material and laminated to the foil  130.  One such holding force can be a vacuum force  222  applied to the solder balls  320  through the openings  202  in a foil  130.  After locating the solder balls  320  at electronic pads  910  or  1010  on a component  900  or substrate  1000,  by removing the holding force  222,  the solder balls  320  are released and placed on the electronic pads  910, 1010.  Optionally, a plurality of pins may provide a releasing and/or placing force.

This is a continuation of Ser. No. 08/832,288 filed Apr. 3, 1997, nowU.S. Pat. No. 6,230,963, issued May 15, 2001 and is included herein byreference.

The parent application (Ser. No. 08/832,288) is a continuation-in-partof Ser. No. 08/789,883 filed Jan. 28, 1997, now U.S. Pat. No. 6,202,918issued Mar. 20, 2001 and included herein by reference.

FIELD OF THE INVENTION

This invention relates in general to the field of conductive preformplacement systems for surface mount technology, and in particular to amethod and apparatus for placing solder balls on electronic pads thatare on a substrate such as for a ball grid array (BGA) applicator.

BACKGROUND OF THE INVENTION

Conventional methods for manufacturing surface mount components, or formanufacturing circuit supporting substrates for surface mountcomponents, typically include methods for placing conductive preforms,e.g., solder balls, solder spheres, and preformed solder bumps, onelectronic pads arranged in a predetermined placement pattern that issometimes called a ball grid array (BGA).

A known method for placing solder bumps on electronic pads on asubstrate utilizes a stencil placed over the electronic pads on thesubstrate to guide solder paste to flow through openings in the stencilplate onto the electronic pads. The solder paste is typically spreadover the stencil using a squeegee to remove the excess solder paste.After the stencil is removed from the substrate, solder bumps are formedon, and remain attached to, the electronic pads. This method technicallyforms the solder bumps on the electronic pads and does not place solderthat has been preformed on the electronic pads.

The solder paste, as formed in this method, has a tendency to developinternal structural defects, such as voids, or variation of fused soldervolumes during the fusing process, thereby introducing potential defectsto the manufacturing process and/or risk of failure during the life ofthe product. This is an undesirable consequence of this method.

A first known method for placing solder balls on electronic pads on asubstrate utilizes a stencil plate placed over the electronic pads onthe substrate to guide solder balls to drop through openings in thestencil plate onto the electronic pads. The electronic pads having beenpre-printed with solder paste, the solder balls then adhere to theelectronic pads via the solder paste. During a reflow operation, thesolder balls fuse to the electronic pads on the substrate.

Besides requiring a guiding force to reliably introduce the solder ballsinto the openings in the stencil plate, this method additionally suffersfrom a hot-air knife reflow heating step that unevenly distributes heatover the solder balls in the stencil plate. Further, the heating stepapplied while the solder balls are in the stencil may cause the solderto melt and adhere to the stencil. Furthermore, a heating-knife motioncontrol mechanism can be expensive.

A second known method for placing solder balls on electronic pads on asubstrate utilizes tubes to hold the solder balls over the electronicpads. Each tube applies a vacuum force to hold a solder ball to the endof the tube. After locating the tubes holding the solder balls over theelectronic pads, the solder balls are placed on the electronic pads byremoving the vacuum force from the tubes and vertically vibrating thetubes to release the solder balls onto the electronic pads.

The apparatus for this second method tends to be complicated and can beexpensive to produce and maintain. Since the solder balls are placedsequentially, the process is not conducive to cycle time. It also maynot be suitable for micro-BGA placement where the pitch of the pads isvery fine and requires tight tolerances in locating the solder spheres.

A third known method for placing solder balls on electronic pads on asubstrate utilizes a plate with solder bumps attached to the plate in apattern corresponding to the pattern of the electronic pads on thesubstrate. The solder bumps are attached to the plate by etching apattern of openings in a photoresist mask over the plate according to apredefined artwork, and then depositing solder composition on the plateat the openings (where the plate surface is exposed) by anelectroplating operation. Lastly, after removing the photoresist layer,the solder bumps remain attached to plate. The solder bumps are thenplaced on the electronic pads on the substrate by positioning the plateover the electronic pads to allow the solder bumps to contact theelectronic pads. By heating the entire assembly, the solder bumps meltand transfer onto the electronic pads.

Besides constituting a relatively expensive process to implement in amass production environment or use for occasional rework, this methodrequires trained operators to perform numerous steps, including chemicalprocessing steps that can subject an operator to environmental hazards.The overall process, therefore, can be environmentally unfriendly, timeconsuming, expensive, and generally requiring trained operators to beeffective.

The use of Ball Grid Array technology is increasing as the advantages ofthe interconnect process are recognized. The disadvantage of thistechnology is where rework or salvage of components using Ball GridArray technology is required; once the component is removed a portion ofthe solder preforms remains on the component and a portion of the solderpreforms remains on the Printed Circuit Board (PCB). Thus, what isnecessary is a low cost and efficient method and apparatus for placingconductive preforms on pads on a component, or on a substrate.

SUMMARY OF THE INVENTION

One aspect of the present invention is to provide a low cost tool forlocating and placing the conductive preforms onto the pads of substratesor components. The tool preferably comprises a foil structure thatincludes a plurality of openings that are used to locate, hold, andplace the conductive preforms onto the pads.

Another aspect of the present invention is the use of current state ofthe art technology, including artwork and a photodeveloping and etchingprocess on the foil to create the openings. This process eliminatessignificant variation in locating and forming the openings in the foilwhile maintaining a low cost for the tool. As the distance between thecenters of the pads (pitch) decreases, such as for fine pitch, or microBGA (μBGA) manufacturing, the variation in locating and shaping theopenings becomes significantly more critical for maintaining an accurateand reliable conductive preform placement process.

Another aspect of the present invention is the ability to facilitatechanging a pattern of openings on a foil for placing conductive preformson different arrangements (patterns) of pads. By using different foilswith different etched patterns (different patterns of openings etched inthe foils), the low cost tool can efficiently place conductive preformson different patterns of pads on a substrate.

Another aspect of the present invention is the ability to utilize oneaperture pattern and modify the placed pattern of preforms by filling orcovering the undesirable apertures. The material partially covering thefirst foil aperture can increase the reliability of filler materiallocated inside the undesired apertures of the foil.

Another aspect of the present invention is the ability to include amechanism to hold the conductive preforms at the openings in the foiland then remove the holding force to place the conductive preforms onthe pads.

Another aspect of the present invention is the ability to allow flow ofa vacuum force to the apertures of the foil.

Another aspect of the present invention is the ability to utilizeapertures which are used to locate the conductive preforms, inconjunction with a second feature which retains the preform fromentering the vacuum chamber. This aspect ensures release of theconductive preforms. The feature which controls the distance which thepreforms enter into the vacuum chamber can be, but not limited to afabric mesh, a screen, a second foil of either metal, mylar, Polyimide,or any other known material with smaller apertures, or any porousmaterial.

Another aspect of the present invention is the ability to create adifference in the size of the apertures on each side of the foil (ataper in the cross section of the openings of the foil) to attain abetter process for accounting for tolerances, securing, and releasingthe conductive preforms. The degree of taper can preferably be varied bymodifying the artwork for the two opposing sides of the foil.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a Ball Grid Array Applicator apparatus,according to a preferred embodiment of the present invention.

FIG. 2 is an isometric view of a foil and block structure representing aportion of a conductive preform placement apparatus, according to apreferred embodiment of the present invention.

FIG. 3 is a cross sectional view of the foil and block structure of FIG.2, additionally showing solder spheres being held at openings in thefoil and the flow through backing media.

FIG. 4 is a bottom side plan view of a block structure constructed inaccordance with a preferred embodiment of the present invention.

FIGS. 5, 6, 7 and 8 are cross-sectional side views of a foil andrepresent steps in making the foil according to a preferred embodimentof the present invention.

FIG. 9 is an isometric view of a foil illustrating the relation of asample porous material, an aperture and a solder sphere according to thepreferred embodiment of the present invention.

FIG. 10 is an isometric view of multiple foils illustrating the relationof the first locating foil with a pattern aperture and a second backingfoil with a smaller backing aperture and a solder sphere according to analternate embodiment of the present invention.

FIG. 11 is an isometric view of a foil located in proximity with acomponent.

FIG. 12 is a cross-sectional side view of a component installed on acircuit supporting substrate.

FIG. 13 is a flow diagram for a manufacturing process for a ball gridarray applicator, according to a preferred embodiment of the presentinvention.

FIG. 14 is an operational flow diagram illustrating a method, accordingto a preferred embodiment, for using the ball grid array applicator toplace solder balls onto pads.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates an isometric view of a Ball Grid Array (BGA)applicator 100 in accordance with a preferred embodiment of the presentinvention. A platform 110 supports an alignment plate 115 and areservoir 120 to contain said conductive preforms 125.

In a preferred manual configuration, the placement apparatus 132 isaligned to the component (not shown) by placing the component into thecavity 118 in the component alignment plate 115. The component alignmentplate is registered to the placement apparatus 132 by use of alignmentpins 140 through alignment holes 142 in the component alignment plate115 and the placement apparatus alignment holes 144 in the placementapparatus 132. Optionally release springs 145 may be included to assistwith separating the placement apparatus from the component. Thealignment pins 142 can be optionally used for alignment of the stencil(not shown) for applying a pattern of tacking media, such as epoxy,flux, solder paste, or similar (not shown) to correspond to the pattern134 of the placement foil 130 of the placement block structure 132.

In an automatic configuration, an automated equipment, or a robotic armand end-effector, (not shown) could constitute the movable placementapparatus 120 that automatically moves along the axis substantiallyperpendicular to the alignment plate 115 according to a predeterminedoperational sequence, such as a programmed set of instructions at arobotic station (not shown).

A foil 130 with a pattern 134 is coupled to a block structure 132according to a construction and arrangement that will be fully discussedbelow.

In a preferred configuration of the BGA applicator 100, two aligningpins 140 are affixed on, and perpendicular to, the platform 110 tocooperatively mate with alignment apertures 142 in the alignment plate115, and alignment apertures 144 in the block structure 132. Thealigning pins 140 mate with the alignment apertures 144 to provide areliable alignment mechanism for the block structure 132 and thecomponent alignment plate 115, thus reliably aligning the placementpattern 134 to the desired location on the component (not shown).Additionally, the block structure 132 and the alignment plate 115 can beinterchanged with others of different patterns, insuring repeatablealignment.

In one embodiment, a vacuum source 150 is coupled to a port (not shown)in the block structure 132, such as via a flexible hose 152 andconnectors 154, 156. The vacuum source 150, when activated, delivers afirst vacuum force to the port in the block structure 132. Whendeactivated, the vacuum source 150 then delivers a second (zero) vacuumforce to the port in the block structure 132. In this way, a vacuumforce can be applied to the port in the block structure 132 for aplacement operational sequence using the placement pattern 134 in thefoil 130 and block structure 132, as will be more fully discussed below.

Referring to FIG. 2, according to a preferred embodiment of the presentinvention, a foil 130 is coupled to a block structure 132. The foil 130has a pattern of openings 202 created therein to match a pattern of pads(not shown) located on a substrate (not shown), such as to match apattern of electronic pads on a component or on a circuit supportingsubstrate. Preferably, the pattern of openings 202 is created using anetching process with a predefined artwork for accurately locating andshaping the openings, as will be more fully discussed below.

The block structure 132 includes a main vacuum port 220 of the blockstructure 132 and pneumatically coupled to an external vacuum source 150(see FIG. 1). A vacuum force 222 is provided through the vacuum port 220and thereby routed through an expansion area (not shown) to the patternof openings 202 in the foil 130. It can be recognized that the optimalvacuum flow 222 to the pattern of apertures 202, where the design limitsthe minimal cross section for any point of the vacuum routing system tobe greater than the sum of the area of the maximum number of apertures.The completed block assembly is illustrated as 200.

FIG. 3 is a cross-sectional view of the block structure 300 and firstfoil 310 shown respectively within the apparatus as 132, 130 of FIG. 1,illustrating solder spheres 320 positioned in openings 322 in the firstfoil 310 respectively representing the pattern 202 in the foil 130 (seeFIG. 2). The solder spheres 320 are arranged in the apertures 322 (shownwith an optional trapezoidally shaped cross sectional) of the foil 310.A vacuum force 222 is provided to the vacuum port 220 and thereby routedthrough a vacuum expansion area 330 to the pattern of openings 322 inthe foil 310. The force of a vacuum to locate and hold the solderspheres into a foil is capable of mechanically coupling the soldersphere 320 within the aperture 322 of the foil 310 impeding completerelease of the solder spheres. This scenario can be avoided by includinga solder sphere backing material 340 located between the vacuumexpansion area 330 and the foil 310 where the material 340 is used tocontrol the distance which the solder spheres 320 can penetrate into thevacuum expansion area 340. The preferred embodiment of the inventiondescribes using a mesh fabric material for the solder sphere backingmaterial, while it can be recognized that any porous material 340 whereat least a portion of the material 340 covers a portion of the aperture322 in the foil 320. The solder backing material 340 allows for a crosssectional dimension of the apertures 322 to be larger than the crosssectional dimensions of the solder spheres 320. The backing material 340must be assembled in a manner where the backing material 340 does not_significantly deflect from the foil 310 when exposed to the force of thesolder spheres as created by the flow of the vacuum system. The backingmaterial 340 can be made of a stiff material, bonded directly to thesurface of the foil 320 or supported by including a second foil 350,similar to 310. This feature provides for release of the solder spheres320 from the apertures 322 of the foil 310 without use of any additionalforces, resulting in a very simple, repeatable, and low cost apparatusand method.

An alternative assembly to obtain the same feature for release of thesolder spheres would be to reduce the apertures of the second foil 350to control the distance where the solder spheres 320 penetrate into thevacuum expansion area 330.

FIG. 4 is a bottom side plan view of a block structure constructed inaccordance with a preferred embodiment of the present invention. Thebottom side plan view of the block structure illustrates the outline ofthe block structure 400, the vacuum chamber 410, bottom of the vacuumexpansion area 420, and top of the vacuum expansion area 425.

FIGS. 5, 6, 7 and 8 are cross-sectional side views of a foil andrepresent steps in making the foil according to a preferred embodimentof the present invention. Although the steps represented by FIGS. 5,6,7,and 8 describe a preferred embodiment of the present invention, one canrecognize that other processes such as laser drilling or materialbuildup or other methods can be alternatively used to create the foil.

FIG. 5 illustrates the raw material for the foil 500 in pre-etchedstate. The raw material for the foil 500 may consist of, but is notlimited to stainless steel, brass, polyimide, mylar, copper, nickel,etc. Phototooling 510 is laminated to both sides of the raw material forthe foil 500. Phototooling 510 can be described as a chemical ormaterial that changes state (develops) when exposed to a light source.The artwork 520 is placed on both sides of the foil above the phototool510. The artwork 520 blocks the light from the phototooling resulting inthe transfer of the desired pattern. The phototooling 510 which isexposed to light is cured and the phototooling 510 which is not exposedto light is not cured and later removed, resulting in a negative of thepattern on the foil. The pattern 530 on one side of the foil maypurposely be of a different size compared to the pattern 535 on theopposing side.

FIG. 6 illustrates the raw material of the foil 500 prepared to bechemically etched. The raw material of the foil 500 has the exposedphototooling 610, 615 after the artwork 520 (not shown) has been.removed, a pattern 620 on one side, and a pattern of optionallydifferent size 625 on the opposing side. The raw material of the foil500 with the laminated, developed phototooling 610, 615 is subjected asan assembly to a chemical 630 with properties which remove the rawmaterial of the foil 500 not coated with developed phototooling 620 and625.

FIG. 7 illustrates a cross section of the foil 700 in a post etch state.The removed material creates an aperture 710. The resultant optionaltrapezoidal cross section 720 is illustrated as created by utilizing theoptionally different sized patterns 610 and 615 on opposing sides of thefoil 700.

FIG. 8 illustrates a cross section of the foil 800 in a post etch statewith the phototooling removed. The pattern 810 can optionally beenhanced by additional post etch processing including but not limited toplating alternative materials such as Teflon, copper, silver, nickel, orgold to the etched foil or electropolishing the etched foil.

FIG. 9 is an isometric view illustrating how the flow of the vacuum (notshown) holds a solder sphere 900 against the screen mesh 930 andcontained within the aperture 910 created in the foil 920. It can betaught that the use of any material which partially covers the apertureto hold the sphere from entering into the vacuum cavity can be used.

FIG. 10 is an isometric view demonstrating an alternative embodiment ofthe invention, illustrating how the flow of the vacuum (not shown)through a vacuum aperture 1020 in a second foil 1025 holds a soldersphere 1000 against an area 1030 of a second foil 1025 overlapping anarea of a containing aperture 1010 and contained within the containingaperture 1010 created in a first foil 1015.

FIG. 11 illustrates a foil 130 coupled to a block structure 132 locatedin proximity with a component 900. The pattern of openings 210 in thefoil 130 is created to match a pattern of pads 910 located on thecomponent 1100. Preferably, the pattern of openings 1110 is createdusing predefined artwork and a photodeveloping and a chemical etchingprocess.

FIG. 12 is a view of the component 1100 and a corresponding receivingcircuit supporting substrate 1200. The pads 1110 on the component 1100are typically pre-bumped with conductive preforms, such as with solderballs 1250. When the component 1100 is placed on the circuit supportingsubstrate 1200, the solder balls 1250 electrically and mechanicallycouple the pads 1110 on the component 1100 and the pads 1210 on thecircuit supporting substrate 1200.

FIG. 13 is a flow diagram 1300 illustrating a preferred manufacturingprocess for the foil 130 and the block structure 132 of the BGAapplicator 100, according to a preferred embodiment of the presentinvention. The manufacturing process describes a method 1310 for toolingthe foil 130 and a method 1330 for tooling the block 132. Numerousmethods to create apertures within a foil are well known, with the mostcommon described in the process flow 1310. The first step 1312 to createthe foil 130 is to create artwork with the required pattern. Twoartworks 520 are required, one for each side of the foil 130. Theartwork 520 can optionally be created such that the diameter of eachcircle of the pattern on the first artwork 530 is different from thecorresponding circles of the pattern on the second artwork 535. Thisdifference results in a trapezoidal cross section 720 when the foil isetched. The second step 1314 to create the foil 130 is to laminate thephototooling 520 onto both sides of the raw material of the foil 500,develop the phototooling 520, and remove the non-developed portion ofthe phototooling leaving exposed metal 620 and 625. Once completed thephototooling creates a negative of the pattern on the raw material ofthe foil 500. The third step 1316 to create the foil 130 is to removethe exposed metal 620 and 625 by a chemically etching process. The forthand final step 1118 to create the foil 130 is to remove the phototooling610, 615. The first step 1332 to create the block structure 132 is toform the block by either molding, machining or similar. The second step1334 to create the block structure 132 is to stretch screen material 340and attach the screen material 340 to the block 132. Alternatively, thescreen material 340 can be adhered to the foil 130. Upon completion ofthe foil 130 and the block structure 132, the next step 1350 is tocouple the two assemblies together to complete the apparatus 200. Thefinal step 1360 would be to install the apparatus 200 onto the vacuumsource 150 via a flexible hose 152 and connectors 154, 156.

FIG. 14 is an operational flow diagram 1400 demonstrating the method ofapplying the conductive preforms to a pattern of pads 1110 or 1210. Thefirst step 1410 to applying the solder spheres 320 is to create a vacuum222 within the vacuum chamber 220 and the vacuum expansion chamber 330.The second step 1420 is to expose the apparatus 200 to a reservoir 120of loose conductive preforms 125, where the preferred embodiment wouldbe solder spheres 320. The third step 1430 results from the second step1450 where the flow from the vacuum will lift the loose solder spheres320 and hold one sphere per aperture 322 of the pattern 202. The forthstep 1440, 1450 is to apply a media which is used to temporarily securethe solder spheres 320 to either the pads 1110 on the component 1100 orthe pads 1210 on the receiving substrate 1200. One method 1440 which canbe used would be to apply a media (flux, solder paste, conductive epoxy,etc.) directly to the receiving pads by dispensing, screen printing orother well known processes. A screen printing process can utilize thealignment pins 140 by including alignment apertures similar to 142 ofthe alignment plate 115 on a flux/solder paste printing foil (notshown). An alternative method 1450 which can be used is to dip thesolder spheres 320 into a trough with a predetermined thickness of themedia. The fifth step 1460 to applying the solder spheres 320 is toplace the solder spheres onto the receiving pads 1110 or 1210. Aligningpins 140 and the component alignment plate 115 can be used to assist inproperly aligning solder spheres 320 to the pads 1110 on the component1100 or pads 1210 on the substrate 1200. The sixth step 1470 to applyingthe solder spheres 320 to the receiving pads 1110 or 1210 is to releasethe solder spheres 320 from the apparatus 200 by applying a zero vacuumforce 222 and/or using the tact of the securing media. The seventh step1480 to applying the solder spheres 320 to the receiving pads 1110 or1210 is to separate the apparatus 200 from the component 1100 or thesubstrate 1200, leaving the conductive preforms within the securingmedia. The ninth step 1490 in the process is to optionally remove thecomponent from the apparatus and bond the solder spheres 320 to thereceiving pads 1110 or 1210. The bonding process would be respective ofthe material used for the securing media. Some examples would be reflowfor flux or solder paste or curing for conductive epoxy.

What is claimed is:
 1. A method for placing a plurality of conductivepreforms on a plurality of electronic pads, the method comprising thesteps of: holding a plurality of conductive preforms at least partiallywithin a plurality of openings in at least one foil, wherein theopenings in at least one foil have at least one exposed diameter that isequal to or larger then the diameter of the conductive preforms andagainst a porous member which at least partially covers at least aportion of the plurality of openings of the foil; locating the pluralityof conductive preforms to the plurality of electronic pads; and placingthe plurality of conductive preforms from the at least one foil andporous member on the plurality of electronic pads by removing the meansfor holding the solder spheres from the plurality of openings in the atleast one foil.
 2. The method of claim 1, the method further comprisingthe step of inspecting the completeness of the conductive preformswithin the at least one foil.
 3. The method of claim 1, wherein theplacing step comprises the step of: applying placing force to theplurality of conductive preforms in the direction of the plurality ofelectronic pads.
 4. An apparatus for placing a plurality of conductivepreforms on a plurality of electronic pads, the apparatus comprising: atleast one foil including a plurality of openings, wherein the openingshave at least one exposed diameter that is equal to or larger then thediameter of the conductive preforms; a porous member positioned in amanner such to at least partially cover at least a portion of theplurality of openings of the foil, whereby the porous member is used tocontain the conductive preforms at least partially within the openingsof the foil; and a means for removably providing a holding force to theplurality of conductive preforms for holding the plurality of conductivepreforms at least partially within the plurality of openings and forplacing the plurality of conductive preforms on a plurality ofelectronic pads on a substrate by removing the holding force from theplurality of conductive preforms.
 5. The apparatus of claim 4, whereinthe foil is manufactured from one of the following materials: (a)Stainless Steel; (b) Brass; (c) Nickel; (d) Polyimide; and (e) a thinstrong polyester film.
 6. The apparatus of claim 4, wherein theplurality of openings in the foil are constructed using at least one ofthe following production processes: (a) chemically etching the foilutilizing predefined artwork masking for the pattern of the plurality ofopenings; (b) laser drilling the foil utilizing a predefined pattern fordrilling the plurality of openings; (c) mechanically drilling the foilutilizing a predefined pattern for drilling the plurality of openings;and (d) polishing the foil.
 7. The apparatus of claim 4, wherein theporous member consists of one of the following materials: (a) Wovenfabric; (b) Polyester mesh; (c) Silk screen; (d) Metal screening; and(e) A sponge type material.
 8. The apparatus of claim 4, wherein theporous member is at least partially adhered to the foil.
 9. Theapparatus of claim 4, wherein the apparatus further comprising a secondfoil with a plurality of apertures and the porous member is containedbetween the first foil and second foil.
 10. The apparatus of claim 4,wherein the porous member is a metal plate with a plurality of openings.11. The apparatus of claim 4, where the dimensions of the aperture onone side of the foil differ from the dimensions of the aperture on theopposing side of the aperture.
 12. An apparatus for placing a pluralityof conductive preforms on a plurality of electronic pads, the apparatuscomprising: at least one foil including a plurality of openings whereinthe openings have at least one exposed diameter that is equal to orlarger then the diameter of the conductive preforms; a porous memberlocate proximate the at least one foil and which covers at least aportion of the openings of the foil therein, whereby the plurality ofconductive preforms are held at least partially within the plurality ofopenings of the at least one foil and held against the porous member bya removable vacuum holding force whereby the plurality of conductivepreforms can be transferred to the electronic pads of a receivingsubstrate within the apparatus as described and placed by removing thevacuum holding force; and a block structure including a chamber fordistributing the vacuum holding force across the plurality of openingsof the foil.
 13. The apparatus of claim 12, wherein the plurality ofopenings in the foil are constructed using at least one of the followingproduction processes: (a) chemically etching the foil utilizingpredefined artwork masking for the pattern of the plurality of openings;(b) laser drilling the foil utilizing a predefined pattern for drillingthe plurality of openings; (c) mechanically drilling the foil utilizinga predefined pattern for drilling the plurality of openings; (d)polishing the foil; and (e) plating the foil with a metallic surfaceincluding at least one of the following: gold plating, silver plating,copper plating, nickel plating, and polytetrafluoroethylene plating. 14.The apparatus of claim 12, wherein the porous member consists of one ofthe following materials: (a) Woven fabric; (b) Polyester mesh; (c) Silkscreen; (d) Metal screening.
 15. The apparatus of claim 12, wherein theapparatus further comprising a second foil with a plurality of aperturesand the porous member is contained between the first foil and secondfoil.
 16. The apparatus of claim 12, wherein the porous member is ametal plate with a plurality of openings.
 17. The apparatus of claim 12,where the dimensions of the aperture on one side of the foil differ fromthe dimensions of the aperture on the opposing side of the aperture. 18.The apparatus of claim 4, the apparatus further comprising a means forapplying at least one of a placing and releasing force to the pluralityof conductive preforms.
 19. The apparatus of claim 18 wherein the meansfor applying at least one of a placing and releasing force to theplurality of conductive preforms is a plurality of pins.
 20. Theapparatus of claim 10, the apparatus further comprising a means forapplying at least one of a placing and releasing force to the pluralityof conductive preforms.
 21. The apparatus of claim 20 wherein the meansfor applying at least one of a placing and releasing force to theplurality of conductive preforms is a plurality of pins.
 22. A method ofplacing a pattern of solder spheres at predetermined positions on asubstrate using a foil with a plurality of apertures and a second,movable member, the method comprising steps of: loading solder spheresinto the foil while the foil is in a substantially horizontal positionand holding the solder spheres against the second, movable member;positioning the substrate beneath the carrier plate; moving the second,movable member to aid in the release of the solder spheres; and pushingthe solder spheres through the holes in the foil and onto the substrate.23. The method of claim 22, further comprising a step of using a visioninspection method after the step of loading and before the step ofpushing to verify that each of the holes contains a solder spheres. 24.The method of claim 23, whereby the surface of the foil is treated toprovide contrast to the solder spheres to assist in the visioninspection method.
 25. A method of placing solder balls on a substratecomprising the steps of: providing a foil with a plurality of holes,each hole capable of holding a solder ball; treating the surface of thefoil to change the surface of the foil such to aid in the inspectionprocess of the solder spheres; and pushing a pattern of solder ballsfrom the foil to the substrate with a flexible protrusions of a ballplacement head that are aligned by an alignment means.